1. Field of the Invention
This invention relates to a solid-state image pick-up apparatus and more particularly to a solid-state image pick-up apparatus arranged to have a variable image pick-up magnification.
2. Description of the Related Art
In changing the image pick-up magnification of an image pick-up apparatus, it has been practiced, for example, to change the magnification of an optical system as in the case of a zoom lens. This practice has resulted in the complex structural arrangement of the optical system and thus hindered efforts to reduce the size and weight of the apparatus. Meanwhile, there has been proposed a method of obtaining, for example, a zooming function by varying the read-out range of addresses of a solid-state image sensor as disclosed in Japanese Laid-Open Patent Application No. Sho 57-136872.
In the method of changing the read-out address range of a solid-state image sensor in obtaining, for example, a zooming function, the data of all the picture elements is read out in the case of a small image pick-up magnification while the data of only some of the picture elements is read out in the event of a large image pick-up magnification. With the range of read-out addresses thus arranged to vary with the image pick-up magnification, however, the amount of read-out picture element data varies. Therefore, in reading picture element data in a given cycle of the standard TV signal, a reading clock signal frequency must be changed accordingly as the image pick-up magnification varies. Then, the frequency band of an image signal obtained by such reading comes to be changed by the difference arising in the image pick-up magnification. This necessitates some change in the signal processing method to eliminate such inconvenience. The prior art method thus has presented a problem in terms of practicability.